Ultra high frequency mixer circuit



July 5, 1949. A. VAN WEEL ULTRA HIGH FREQUENCY MIXER CIRCUIT Filed F'eb.12, 1947 A. VAN WEEL INVE NTO R MM7 'ACENT J oscillatory circuit 2, 2 aswell as of the said in-phase circuit may be reduced, provided that thesaid impedances are adjusted to a correct" va1ue. This feed-backcoupling may be enhanced te such extent that there are predued eitherescillations of a frequency corresponding te the frequency te which thepush-pull oscillatory cir" cuit is tuned and which oscillations may betransmitted directly by the receiving aerial l l, er oscillations whosefrequency corresponds te the frequency te which the in-phase circuitmentiened before is tuned and. which osciilations thereforemay be usedas the local oscillatiens in the reception. It is even fundamentaliypessible te preduce simultaneeusly the escillations te be transmittedand the local oscillatiens serving for the receptien, so that atransmissien and a reception can take place, and if desiredsimultaneeusly, without any swtching-ever operation. As a ru1e,hewever,it is desired te produce only one of thetwe oscillations. Inthis case one or more of the ieed-back impedances may adventageeusly bemade inoperative by short-circuitingeras an alternative dampingresistances may be includedin one of the circuits, (push-pull circuit,in-phase circuit), the construction being such thatthe preductien ofeither iecal oscillatiens er oscillations te be transmitted is aveided.

Now, accerding te the invention, the frequency of the oscillations te betransmitted and the frequency of the local oscillatiens are bothestablished by theuse efthe box circuit E3 which has beenmentienedbefore. This box circuit comprises two inner cenductors I and 18'arranged symmetricaliy, tegether with four adjustable cencentratedcapacities H, 12', 12' and E3. The box circuit has twe tunings, viz, oneas the pushpulicircuit andthe ether as the in-phase circuit. Byregulating the capacity 1 l it is possible to vary the frequency of thepush-pull circuit,

whereas the frequency of the in-phase circuit may be adjusted byregulating thecapacity l3. With the adef the capacities 12 and H acorrect symmetrical arrangement may beobtained. The anedes of the mixingsystems are cennected te the box circuit in points A and A, the extentte which the mixing systems are coup1ed te the boxcircuit being in thefirst piace dependent en the p1aces of the points A'- and A and furtheron the values of the impedances 5, 8 and 8. Since, as a rule, the piacesof the points A' and. A are fixed once or 2111, the adjustment of theceupling is effected solely with the aid of the said impedances. By asuitable cheice of these impedances it is possible fer the ceupling ofthe mixing systems with the box circuit-te be adjusted diferently fereach of the modes of escillation, ewing te which the extentofstabilisation obtained fer the push-pull circuit is diierent frem thatfor the in-phase circuit.

the ceupling becomes strenger and the stabilisa= tien becomeslesssatsfactery.

If the impedance 5 is given a capacitative value, only the coupling ferthe in-phase oscillation becemes 1ess streng and hence the stabilisatienbecomes better (with an inductive value of the irnpedance 5theceupling.becomes strenger, etc.). The extent of stabilisation of thetwo kinds of oscillation may therefore be fully controlled by a suitablechoice of the three said impedances.

Fig. 2 shows a circuit arrangement fer receiving electricalultrahigh-frequency oscillatiens in which in a similar manner use ismade of a box circuit as in the circuit shewn in Fig. 1. In this case,however, the box circuit is used te improve the selectivity of thepush-pull input circuit. For this purpose the dipole aerial I, I iscennected in points B and B" to the inner conducters H3, H1 of the boxcircuit, whereas the control grids of the mixing triodes 3, 3 arecennected in peints C and C te the said nner cenductors.

As befere, the local oscillatiens are produced by the circuititselfandthis owing te the backcoupling by means oianinductance 0011 Hicated between the junction of the two cathedes and the junction oftwecendensers and 15' interpesed betweenthe anedes of the mixing systems3 and 3. The frequency of the local osciliations is nowstabilised in asimilar manner as in the circuit of Fig, 1, evenif the box circuit 9 isiocated between the contrel grids and the cathodes and not between theanodes and the cen trol grids of the mixing triodes.

Instead of cennecting the aerial directly te the box circuit inthepeints B, B, it is also possible for the aerial te be cennected,threugh small ca pacities, te the contro1 grids of the two tubes.

In a circuit which utilizes a box circuit te enhance the selectivityefthe input circuit, the box circuit may alternatively be arrangedbetween the anodes asinthe circuits shown in Fig. 1. However, use ispreferably made of a circuit arrangement of the kind shewn in Figu1e 2.

What I claim.isz

1. A mixing circuit for combining lecal oscii- 1atiens with high:frequency esciilations compris ing a pair of electron discharge tubeshaving first and-second input electredes and an output electrode, enepair of corresponding input electredes being interconnected, an.inputcircuit cennected between the other..pair of corresponding electredesfer applying:the high frequency osciliatiens thereto in push-pullrelation, an auxiliary circuit cennected between said interconnectionand the electrical centerofsaidinput circuit fer applying 1ocalescillations tosaid.other pair of cerresponding electredes te cephasalrelation, an

output circuit cennected between the output electredes of said tubes ferderiving the intermediate oscillationstherefrom, and -means te stabilizethe mixing circuit fer said 1ocal and high frequency oscillations, saidstabilizing means including an enclesedt tubular outer conductor, a pairof symmetrically disposed inner conducters cennected te one end ef saidouter conductor, said outer conductor being cennected te an intermediatepoint in said auxiliary circuit, means cennecting said inner "cenducters1espectively te the anedes of said tubes, a capacitance between saidinner conductors having a value eiecting resenance at thefrequency ofsaid high frequency escillations and a capacitance between said innerconductorsandsaid outer conductorhaving a. va1ue eiecting resonance atthe frequency of-1ocal oscillations.

2. An arrangement, as Sset forth in claim 1, wherein said capacitancebetweensaid inner conductor and said outer conductor is constituted by apair of series-connected capacitors connected between the free ends ofsaid inner conductors, and a capacitor connected between said outerconductor and the juncture of said series-connected capacitors.

3. A mixing circuit for combning local cscillations with high frequencyoscillations to produce intermediate frequency oscillations comprising apair of. electron discharge tubes each having a cathode, a grid and. ananode, means interconnecting said grids, a resonant input circuit tunedto the high frequencies osciilations and connected between the cathodesof said tubes for applying said oscillations thereto in push-pullrelation, a first impedance connected between the electrcal center ofsaid input circuit and. ground, a second impedance connected betweensaid interconnection and ground, said first and second impedances incombination with said input circuit being tuned to the frequency of thelocal oscillations for applying same to said tubes in cophasal relation,an output circuit connected between said anodes for deriving theintermediate frequency oscillations thereirom, and means to stabilizethe mixing circuit for said local and high requency oscillationsincluding an enclosed tubular outer conductor, a pair of symmetricallydisposed inner conductors connected to one end of said outer conductor,said outer conductor being connected to ground, means connecting saidinner conductors respectively to the anodes of said tubes, a capacitancebetween said inner conductors having a value effecting resonance at thefrequency of said high frequency oscillations and a capacitance betweensaid inner conductors and said outer conductors having a value effectingresonance at the frequency of said local oscillations.

4. An arrangement, as set forth in claim 3, wherein said secondimpedance has a va1ue effecting positive feedback for said localoscillations to reduce the damping of the cophasal circuit.

5. An arrangement, as set forth in claim 3, further including animpedance element between ea-ch of said anodes and said output circuit,said elements having values efiecting positive feedback for said highfrequency oscillations to reduce the damping of the push-pull circuit.

6. An arrangement, as set forth in claim 3, further including a pair ofimpedance elements each interposed between one of said anodes and one ofsaid inner conductors, said elements having values eiecting positivefeedback for said high frequency oscllations to produce self-oscillationin the push-pull circuit.

7. A transceiver system for mxing local oscillations with high frequencyoscillations to produce intermediate frequency oscillations and fortransmitting high frequency oscillations, said system comprising a pairof e1ectron dis-charge tubes each having a cathode, a grid and an anode,means interconnecting said grids, a resonant input circuit tuned to thehigh frequencies oscil1ations and connected between the cathodes of saidtubes for applyng said oscillations thereto in push-pull relation, afirst impedance connected between the electrical center of said inputcircuit and. ground, a second impedance connected between saidinterconnection and ground, said first and. second impedances incombination with said input circuit being tuned to the frequency of thelocal oscillations for applying same to said tubes in cophasal re1ation,an output circuit connected between said anodes for derivng theintermediate requency oscillations therefrom, means to stabilize themixing circuit for said local and high frequency oscillations includingan enclosed tubular outer conductor, a pair of symmetrically disposedinner conductors connected to one end of said outer conductor, saidouter conductor being connected to ground, means connecting said innerconductors respectively to the anodes of said tubes, a capacitancebetween said inner conductors having a value effecting resonance at thefrequency of said high frequency oscillations and a capacitance betweensaid inner conductors and said outer conductor having a va1ue effectingresonance at the freequency of said local oscillations, said secondimpedance having a va1ue eiecting positive feedback or said localoscillations to reduce the dampng of the cophasal circuit, and. a pairof impedance elements each interposed between one of said anodes and oneof said inner conductors, said elements having values effecting positivefeedback for said high frequency oscillations to generate osciliationsin the push-pull circuit.

ADELBER'I VAN WEEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

